 Now we're going to talk about transcription, which is the conversion of a piece of double stranded DNA made of AC, G, and T into a single strand of RNA made of AC, G, and U. So here you see it happening. Now notice that the player is involved, so here we have our DNA, and the DNA has to be unwound, and then a single copy of RNA is going to be made of this gene. So we'll talk about the three steps of transcription, initiation, elongation, and termination in a second. I just want to talk about the players. Here you see the enzyme involved is RNA polymerase. So DNA polymerase reads DNA and builds DNA. So that's going to be used during DNA replication. RNA polymerase reads DNA and makes RNA, so critically important here in transcription. Why does transcription exist? DNA is housed and protected in the nucleus. We need this intermediate, the RNA, to get the message from the nucleus to the ribosomes, at least in cells like ours. So that's going to be what RNA polymerase does here. Another thing to note, when I say RNA, what I'm actually saying is mRNA, or messenger RNA. I'll talk in the next video about translation, about the other types of RNA. But if someone's just saying RNA, they are talking about messenger RNA. All right, so here we see the three steps. So initiation, elongation, and termination. Initiation begins there at the promoter sequence of DNA. It's a piece of DNA that says RNA polymerase, start here. Start reading DNA. Start making a copy of RNA. Where you see a T, put an A. Where you see a G, put a C. Where you see an A, here's the key, put a U. Because RNA doesn't have thymine in it, it is replaced by its cousin, uracil. So the promoter sequence is where initiation occurs. Elongation is just RNA polymerase reading DNA and putting the corresponding piece of RNA together until we get to the terminator sequence of DNA, which says stop. So at the end, we're going to have a piece of RNA that ran from the promoter sequence of DNA to the terminator sequence of DNA. Now, in eukaryotes like us, though, we're not done, RNA has to be processed. So at this point, you're going to see this called the primary RNA transcript, or I like to call it the pre-mRNA transcript. So when you process RNA, you clean it up so it's ready to leave the nucleus. Two, three things have to happen. First of all, notice at the top we have exons and introns. You're going to splice out all the introns. How do you remember that? Introns stay in the nucleus. They don't have to leave. Exons exit the nucleus. So you cut all the introns out. Notice at the bottom now we only have exons. The other key things that happen is you put a cap on one end and a tail on the other. So when you process RNA and clean it up in eukaryotes like humans, put a cap on one end, tail on the other, get rid of all the introns. They're cut out and they stay in the nucleus. This is the actual piece of messenger RNA that will snake out of the nucleus and go and find a ribosome where it's translated. Okay, so that is DNA transcription, the conversion of DNA into RNA. In the next video we'll cover translation. I hope this helps. Have a wonderful day. Be blessed.